Abstract This publication is a general introduction to common openhole logging measurements, both wire line and MWD/LWD, and the interpretation of those measurements to determine the traditional analytical goals of porosity, fluid saturation, and lithology/mineralogy. It is arranged by the interpretation goals of the data, rather than by the underlying physics of the measurements. The appendix files contain digital versions of the data from the case studies, a summary guide to the measurements and their interpretation, and a simple spreadsheet containing some of the more common interpretation algorithms. This Second Edition of Basic Well Log Analysis delivers a great impact on training and self-training along with superior workbook exercises, newer measurements, borehole imaging, and nuclear magnetic resonance in separate chapters, all directed to provide a guide through the lengthy and sometimes ambiguous terminology of well logging and petrophysics. It provides readers with interpretation examples (and solutions) so that the techniques described here can be practiced.

Abstract This book provides an overview of the new technical approaches required for best use of horizontal and extended-reach technology in different reservoir situations. The volume is a selection from more than 50 papers presented at an AAPG/SPWLA Hedberg Research Symposium, “International Horizontal and Extended Reach Well Symposium: Focus on the Reservoir,” held in The Woodlands, Texas, on October 10 14, 1999. The 16 chapters describe horizontal and extended-reach wells and drilling programs in a variety of geologic settings all over the world.

Abstract This book provides examples of the use of well logs across a broad range of applications. The “Technology and Techniques” section includes papers on logging in high-angle wells and on logging and imaging while drilling. The “Sedimentology and Stratigraphy” section, introduced by John Doveton (University of Kansas), includes studies from the North West Shelf of Australia, Kalimantan, and Iberia as well as from the North Sea, where important new contributions have been made on the wireline signature of mud rocks. The section on “Fractures and the Stress Field,” with a review paper by Colleen Barton (GMI), includes imaging examples from the North Sea and papers on the characterization of fractures for nuclear-waste disposal. Case histories in the volume come from a wide range of petroleum-related applications and from geotechnical and groundwater studies. Most of the papers were presented originally at the “Geological Applications of Wireline Logs” conference convened by the Geological Society (London) in 1999. The objective of the conference was cross-fertilization of approaches among a range of specialists who use well logs in their work. All users of log data should find inspiration in this volume.

Abstract During the 1990s, many international petroleum companies improved their exploration performance significantly by using principles of risk analysis and portfolio management, in combination with new geotechnologies. While exploration risk cannot be eliminated, it can certainly be reduced substantially, on a portfolio scale. And the widespread adoption of standardized risk analysis methods during the 1990s brought badly needed discipline to petroleum exploration. By the mid-1980s, most well-informed major international petroleum firms that were engaged in exploration recognized that, globally, the average size of new discoveries was diminishing. Not coincidentally, the class of exploratory prospects categorized as “high risk/high-potential” was showing marked signs of underperformance. For major companies, when all such ventures, which averaged around a 10% perceived probability of success, were considered, less than 1% actually discovered profitable oil and gas reserves, and the sizes of these discoveries were generally far smaller than predicted. All in all, such exploration for new giant fields destroyed value, rather than creating it, in the 1980s and early 1990s. Consequently, exploration, as a corporate function, lost credibility. It badly needed to begin delivering on its corporate promises. It needed to become more efficient, and thereby more profitable. To optimize the allocation of exploration capital, concepts of portfolio management began to be considered.

Abstract The production and exploration geologist's best data base for saving time. This is a quick reference to concepts, tools, formulas, and techniques on everything from economics and land leasing to wellsite and engineering methods. If you are in the petroleum geology business this is a must-have volume. “Extensive, well written, well put together handbook for development geologists. The text essentially touches on nearly every topic about which well site geologists or development geologists need to know an extremely complete volume.” Michael D. McCormack, Editor, Geophysics, June 1994

Abstract Application of sequence-stratigraphic analysis depends on the recognition of a hierarchy of stratal units including beds, bedsets, parasequences, parasequence sets, and sequences bounded by chronostratigraphically significant surfaces of erosion, nondeposition, or their correlative surfaces. This method of stratigraphic analysis contrasts with the use of transgressive and regressive cycles of strata for regional correlation of time and facies. Transgressive and regressive cycles have been used for regional correlation for at least 50 years. Recently, proponents of transgressive and regressive cycles, referred to as T-R units, for regional correlation have included Ryer (1983), Busch and Rollins (1984), Busch et al. (1985), and Galloway (1989a). Galloway (1989a) introduced the “genetic stratigraphic sequence,” which is a regressive depositional unit bounded by transgressive surfaces. Although he did not define it specifically, he described it as “a package of sediments recording a significant episode of basin-margin outbuilding and basin filling, bounded by periods of widespread basin margin flooding.”

Abstract The characterization of naturally fractured reservoirs should include core analyses that encompass interpretation of natural and induced fractures. Unfortunately, to date, the differentiation of induced fractures from natural ones in core has been somewhat speculative and often is based on improper techniques. Consequently, bad interpretations have been made and useful information contained in both natural and induced fractures is overlooked. This book addresses the problem of distinguishing natural fractures from induced fractures in both oriented and unoriented core. Natural fractures include any cored fracture that existed in a volume of rock prior to initiation of drilling or coring-related stresses. Induced fractures in core are those that develop during drilling, coring, and subsequent handling. Many of the procedures for distinguishing between the two are based primarily on recognition of fracture surface structures and fracture traces that differ between natural fractures and induced fractures.

Abstract Exploration for petroleum requires much data, and the principles with which to interpret them. Because well and seismic data are extremely expensive in fold and thrust belts, application of simply geometric principles can multiply the effectiveness of geological and geophysical interpretations. Geometry of layerd rocks, expressed by maps, cross sections, and seismic profiles, is the basis for interpreting the geological structure. This publication contains 7 chapters covering thrust faults, generation of folds, and thrust and fold time and sequence from the geometric perspective.

Abstract Will a reservoir produce hydrocarbons? This is a particularly troublesome question in carbonates because, frequently, the answer is anything but straightforward. Despite the best geology put together from carefully crafted depositional and seismic models, only after a well is drilled into a carbonate reservoir, can a geologist decide whether or not the well will give up commercial quantities of hydrocarbons or, indeed, any hydrocarbons at all. Besides information from surrounding wells, data from drill stem tests, cores, cuttings, and open-hole logs ensure the best basis for making a decision about a well's productivity; unfortunately, drill stem tests or core data are not always available so the geologist is forced to fall back on open-hole logs for most of his or her information. Because of unique pore characteristics in carbonate rocks and their affect on resistivity logs, geologists can easily make some incorrect judgements. They sometimes decide a well is productive when it's not, or they sometimes overlook a good well. Problems occur because carbonate reservoirs can have several types of porosity which include intergranular, intercrystalline, vuggy, moldic, and fracture. In addition to these different types of porosity, the pore size may be large (megaporosity) or very small (microporosity). The different pore types and sizes result from both depositional and diagenetic processes.

Abstract In the last few years, our need to answer complex exploration and production questions has led to the use of increasingly sophisticated analytical equipment. Today, the scanning electron microscope (SEM) and energy dispersive X-ray (EDX) systems are being successfully applied to a wide variety of petroleum exploration and production problems. These include: (1) identification of plant and animal mlcrotossils. (for age and environmental interpretations); (2) evaluation of reservoir quality through diagenetic studies; and (3) the investigation of production problems, such as the effect of clay minerals, steamfloods, and chemical treatments on drilling equipment, gravel packs, and the reservoir itself. Although the use and application of the SEM has steadily increased, the amount of reference material available to aid in SEM mineral identification has severely lagged behind. Some textbooks are available which give excellent descriptions of basic SEM theory (Postek et ai, 1980; Wells, 1974), but these books are not written specifically for geologists, so are limited as a geologically oriented SEM work. Papers dealing with the identification of authigenic clay minerals (Wilson and Pittman, 1977) and zeolites (Mumpton and Ormsby, 1976) are an excellent beginning, but no comprehensive guide to mineral identification by SEM has been available. The purpose of this atlas is to provide SEM users (geologists, engineers, geochemists, and technicians) with a beginning guide to SEM mineral identification and interpretation. This atlas by no means contains a complete representation of all common minerals, but rather includes a wide variety of minerals commonly found in clastic reservoir rocks.

Abstract As logging tools and interpretive methods are developing in accuracy and sophistication, they are playing an expanded role in the geological decision–making process. Today, petrophysical log interpretation is one of the most useful and important tools available to a petroleum geologist. Besides their traditional use in exploration to correlate zones and to assist with structure and isopach mapping, logs help define physical rock characteristics such as lithology, porosity, pore geometry, and permeability. Logging data is used to identify productive zones, to determine depth and thickness of zones, to distinguish between oil, gas, or water in a reservoir, and to estimate hydrocarbon reserves. Also, geologic maps developed from log interpretation help with determining facies relationships and drilling locations. As logging tools and interpretive methods are developing in accuracy and sophistication, they are playing an expanded role in the geological decision-making process. Today, petrophysical log interpretation is one of the most useful and important tools available to a petroleum geologist. Besides their traditional use in exploration to correlate zones and to assist with structure and isopach mapping, logs help define physical rock characteristics such as lithology, porosity, pore geometry, and permeability, Logging data is used to identify productive zones, to determine depth and thickness of zones, to distinguish between oil, gas, or water in a reservoir, and to estimate hydrocarbon reserves. Also, geologic maps developed from log interpretation help with determining facies relationships and drilling locations. Of the various types of logs, the ones used most frequently in hydrocarbon exploration are called

Abstract Stratigraphic-trap classifications used in this investigation, follow Rittenhouse (1972). These subtle stratigraphic traps are representative of the type of trap that exploration geologists and geophysicists commonly pursue in the Rocky Mountain basins. If known specific stratigraphic-trap fields can be detected and identified with surface reflection seismic data, then these data may possibly serve as guides to explore for analogous but undiscovered fields. Our approach to documenting the seismic response of the known stratigraphic traps involves three specific steps: (1) simulate the seismic response of a selected stratigraphic-trap field with digital seismic modeling, (2) run vertical seismic profile (VSP) experiments in available wells and dry holes to measure the in situ acoustic properties of both the reservoir and the trap facies, and (3) gather surface seismic data across the field, near available VSP control, to corroborate the model and VSP studies. Each successive stage of the investigation contributes more documentation of the waveform character or seismic signature accompanying the field. The objective of this publication is to present the results of seismic model studies of 15 known stratigraphic traps that were obtained during the first part of the three-fold investigation. The modeled fields have sandstone reservoirs representative of depositional settings, diagenetic histories, and burial depths. Vertical seismic profile and surface seismic experiments will follow where the model studies indicate convincing seismic anomalies. For one of the models, the Red Bird field in the Powder River basin of Wyoming, an entire seismic-stratigraphic investigation is already (Balch et al, 1981).

Abstract First published in 1981, this book was selected to provide the oil industry with a Standard Lithologic Logging System for use in describing cuttings samples from a drilling operation. Roger Swanson developed this manual over years of teaching in the Shell Training Program at Houston. This five-part handbook is the standard for examining and describing samples. Sections include general examination procedures, equipment and techniques, standard abbreviations, comparator charts and graphs, and standard legends and classifications